FilterExpression in query

[obazoud]

Hello,

Is there a way to add an FilterExpression when I query a dynamodb table ?

Thanks

[mikebroberts]

Hi @obazoud - sorry, I missed this question. No, there isn't. DynamoDB filters are only executed client side (not cloud side) and in my experience it's easier to use regular code (e.g. a .filter()) on the query / scan result, rather than use DDB filters. To my knowledge there's no performance drawback in doing so.

[obazoud]

In Amazon DynamoDB, filter expressions are executed server-side after retrieving the items that match the query criteria but before the results are returned to the client. This means that filters reduce the number of items returned but do not affect the number of read capacity units consumed, as all items matching the query criteria are initially read.

[mikebroberts]

Hi @obazoud - OK, you made me go and read up, and you're correct. :) However filter expressions do still have enough limitations that I'm not sure I've ever used them.

I haven't heard of many people using this library, so I don't feel strongly about putting more work in to add this. However if I were to add it I'd probably extend the various Advanced...Options for queries and scans and allow the developer just to specify the precise filter expression that is passed through.